Electronic quartz watches have become very popular in recent times primarily because of their ability to provide a digital read-out coupled with accuracy beyond that heretofore possible with conventional type watches. Essentially, a quartz crystal is used as an oscillator and the output frequency which is extremely stable is divided down into suitable clock pulses for actuating a digital display on the face of the watch.
The display can be provided by light emitting diodes (LED) or liquid crystal displays (LCD).
With either of the foregoing types of displays, no moving parts are required but in each event, an actuating means is required to render the display visible. In the case of the light emitting diode display, the diodes normally remain deenergized since energization thereof is the greatest source of power drain and if they remain illuminated, the power cells would have to be replaced too frequently. On the other hand, the liquid crystal displays are visible at all times but they do not exhibit a great deal of contrast and a light is typically incorporated to increase the contrast of the display. Again, the light does not remain on at all times since this would be too great a power drain.
Thus, with both of the foregoing types of displays, it is necessary and desirable to provide a switch which will close the necessary terminals to effect the desired actuation or illumination as the case may be. The conventional approach accordingly has been to incorporate a manual switch on the watch housing which is pressed to activate or illuminate the display. Unfortunately, the use of a manual switch, which must be actuated by the hand other than the one on which the watch is positioned is often inconvenient and many times impractical or impossible to operate. For example, when driving a car, carrying packages, and so forth it is very inconvenient to attempt to reach over with one hand to actuate the wristwatch switch carried on the wrist of the other hand.
In my copending patent application Ser. No. 516,688 filed Oct. 21, 1974 now U.S. Pat. No. 3,911,666 and entitled ACTUATING MECHANISMS FOR WRIST INSTRUMENTS, I have disclosed and claimed a switch arrangement which may be incorporated in watches of the type which require an actuating means to render the display visible and wherein such switch is operable by a flick of the wearer's wrist so that he need not use his other hand. More particularly, in my referred-to copending application, an electrical contact between appropriate terminals within the watch casing is effected by a hammer-like slug which engages against a springtype contact when the wrist is accelerated and/or decelerated deliberately a sufficient amount to cause a momentary contact between the spring contact and one terminal of the power source in the casing. This same copending application also discloses a pressure type switch which can be actuated by only one hand by pressing a portion of the watch band against a surface.